DE1222243B - Method and device for gluing together a composite consisting of panes of methyl polymethacrylate and a film of polyvinyl butyral located between them - Google Patents

Description

Method and device for gluing together one of panes of methyl polymethacrylate and a film of polyvinyl butyral therebetween existing composite It is known that methyl polymethacrylate sheets or have discs with completely polished surfaces produced, which have an excellent Have transparency and thus other advantageous properties, such as in particular combine low weight and the ability to dampen mechanical vibrations. These properties make such panes particularly suitable as glazing for passenger compartments of vehicles, especially of airplanes.

However, the slightly low surface hardness of the because of its mechanical strength properties commonly used for such purposes Methyl polymethacrylate and the resulting tendency to surface cracks, a significant disadvantage, especially when in contact with solvent vapors, which requires frequent repolishing of the surfaces of such disks.

Besides the methyl polymethacrylates with these properties exists a methyl polymethacrylate, which has such a good surface resistance, that it is possible by gluing together panes made of these two methyl polymethacrylates by means of an intermediate film of polyvinyl butyral glazing, which the Requirements in terms of mechanical strength and surface resistance suffice.

In addition, a process for the production of multilayer glass, d. H. of the "sandwich type", i.e. H. of glasses made by the union of two or several flat or curved glass plates and reinforcement films made of plastic exist, became known. This composite is first under vacuum and then under Heated overpressure.

However, this method is for the production of multilayer glasses within the meaning of the application, which is not made of glass, but of panes of methyl polymethacrylate exist, not applicable.

In the known method, the composite is heated exclusively by convection, which assumes that in the first phase a certain Pressure is present. Only after the disc has a comparatively high temperature has reached 1350 C, the complete vacuum can be established.

Now, however, the internal pressure in the composite drops as a result of the increase in temperature slower than that in the autoclave, which means that at temperatures at which the polyvinyl butyral film has become soft, an overpressure inside the composite prevails.

This overpressure causes the methyl polymethacrylate discs to swell or films; which have become softer and malleable due to the effects of temperature are. With the subsequent pressure treatment, this swelling disappears again, but causes such an expansion that the optical quality of the Disc is finally destroyed.

The causes of the optical disturbances that occur when gluing from Methacrylate films were created, d. H. the temporary swelling of the discs, unknown was.

Optically flawless composites made of methyl polymethacrylate films or discs and a polyvinyl butyral film inserted between them are obtained, while avoiding the above-mentioned inadequacies, thereby that from the composite through a suction device connected to it between The air trapped in the panes and the film is removed, then the composite in a vertical position Position placed in an autoclave, this continuously with constant suction the air trapped between the layers and the film down to the temperature, in which the butyral becomes sticky, is heated and then in a final Phase the autoclave in a known manner pressurized and thereby the bonding is effected.

The cold composite is preferably placed under the action of a vacuum, whereupon heating up to about 1350 while maintaining the effect of the vacuum C takes place, at this point the vacuum is switched off and the air pressure in the autoclave is increased to about 6 kg / cm2.

According to the invention one will usually work with a device the gas-tight seal adhering to the edge areas of the panes, via a pipe socket (5) to a suction device located outside the autoclave is connectable represents.

The seal advantageously consists of a strip of polyvinyl alcohol, which adheres to the panes after simple moistening.

It turns out that by applying the measure according to the invention deformation of the panes even when heated to a temperature that is required is to make the polyvinyl butyral adhesive, so a temperature at which the polymethacrylate plastic, does not occur. There is also the bond between them is effected by a gas pressure without a solid body with the disks in Contact comes, -If their surfaces are not affected, polishing again not necessary.

- It is useful to divide the edge areas of the disks into one of two rigid parts that are clamped together by brackets, existing frame clamp.

For example, according to the method according to the invention, a disk from the methyl polymethacrylate sold under the name »M 33«, which has good mechanical strength properties, with a disc of the im Methyl polymethacrylate available commercially under the name "Oroglass 55", which has a good surface resistance, with the interposition of a film of polyvinyl butyral plasticized by dibutyl sebacate.

First, the butyral is placed under vacuum in the cold. The vacuum is released during the heating until a temperature of about Maintained 1350 C. At this point the vacuum can be switched off and then Air is introduced into the autoclave under a pressure of the order of 6 kgjcm2 that as well as the temperature of 1350 C above that for bonding the panes mutually required time is maintained.

In the intermediate film made of polyvinyl butyral, a network of solid metal wires can be embedded.

The heating glazing produced in this way is sufficient Resilience to allow the disc to warp without the risk of the Allow wire network.

An example embodiment of a glazing according to the invention will now be described with reference to the figures. 1 is an end view the glazing suspended in the vertical position and FIG. 2 shows a section along the line X-X 'of Figure 1; 3 shows a mounting bracket in perspective.

One made from methyl polymethacrylate available under the name »M 33« existing disc 1 of 22 mm thickness and a disc 2 of 2.5 mm thickness from the Methyl polymethacrylate available under the name "Oroglass 55" are interposed a 1 mm thick film of polyvinyl butyral plasticized by dibutyl sebacate on top of each other. The arrangement thus formed is on its entire circumference with a at right angles bent strips 4 of polyvinyl alcohol provided so that the Edge parts of the discs 1 and 2 are covered and the strip 4 adheres to them.

This is done by simply moistening the strip. The stripe forms a gas-tight seal enclosing the film 3. He is with a pipe socket 5 provided, which allows its connection to a suction device.

A rigid frame 6 is placed on each side of this overall arrangement a, 6b made of metal, e.g. B. made of the alloy known under the name »Dural«, arranged, which is placed on the panes 1 and 2 and glued onto them Edge areas of the strip 4 is supported.

On each of the frames is a film 7a, 7b made of a fabric, its Softening temperature is above 1400 C, applied. For this purpose can the polyester available commercially under the name »Terphane« can be used. These films are intended to protect the outer surfaces of the panes 1 and 2 against dust without however, the pressure applied in the manner described below affecting these discs.

Now the two frames 6a, 6b are clamped together of any kind per se, such as those shown in FIG. 3 brackets shown as an example 8, braced together. The purpose of these brackets is twofold. You should on the one hand, press the polymethacrylate discs onto the butyral film and prevent their sliding in relation to each other, on the other hand the films from »Terphane« hold tight. The number of brackets that are required depends on their construction as well as the dimensions of the disks to be combined. The brackets do not act conclusively, so that the pressure inside the autoclave on the surfaces of the panes by the passage of air between the films 7a and 7b and the Frame can act in the spaces between the brackets. If necessary, can Some perforations can also be provided in the films 7.

The assembly thus formed is supported by two hanging irons 9, 10, which by means of chains 11, 12, which converge in a common link 13, are suspended in the autoclave.

Since the heating in the autoclave takes place by forced convection, It is essential to take precautions so that the overall arrangement does not fall short the effect of the air can start to vibrate. Such vibrations must be in the heat to carbonize the tendency of the methyl polymethacrylate, favor. Around To prevent such movements, it is sufficient z. B., on both sides of the overall arrangement to attach two angle irons, each of which has one leg at the bottom of the autoclave and is supported on a post of the frame.

The successive steps to be carried out inside the autoclave Operations have already been described above. Tests have shown that it is useful to increase the temperature up to 1350 C in a period of 40 minutes. There is a period of time for the gluing and gluing process of the order of 20 minutes is required.

Claims (6)

Claims: 1. Method for gluing together a Discs of methyl polymethacrylate and a film between them composed of polyvinyl butyral composite, d a - characterized in that from the composite through a suction device connected to it between the panes and air trapped in the film is removed, then the composite in a vertical position in an autoclave is used, this continuously with constant suction of the air trapped between the panes and the film up to the temperature, in which the butyral becomes tacky, is heated and then in a final Phase the autoclave in a known manner pressurized and thereby the bonding is effected. 2. The method according to claim 1, characterized in that the cold Composite is placed under the action of a vacuum, whereupon while maintaining the Under the effect of vacuum the heating takes place up to about 1350 C, at this point the Vacuum is switched off and the air pressure in the autoclave is increased to about 6 kg / cm2. 3. Apparatus for performing the method according to claim 1 or 2, characterized by one adhering to the edge areas of the panes (1, 2) gas-tight seal (4) connected to an outside of the autoclave via a pipe socket (5) horizontal suction device can be connected. 4. Apparatus according to claim 3, characterized in that the seal (4) from a strip of polyvinyl alcohol, which after simple moistening on the Discs adheres, consists. 5. Apparatus according to claim 3 or 4, characterized in that the edge areas of the disks (1, 2) in one preferably of two rigid with one another clamped parts existing frame (6a, 6b) are clamped. 6. The method of claim 1 using the device according to One of Claims 3 to 5, characterized in that a film is placed on the frame made of a material whose softening point is higher than the working temperature, placed and thereby the overall arrangement to be glued together against the convection currents is protected, but they od via gaps, holes. Like. Under the action of the pressure prevailing in the autoclave. Documents considered: German Patent No. 1 010266.